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November 22, 2011

Researchers Turn Embryonic Stem Cells Into Functioning Neurons

by editor

Scientists from the University of Wisconsin have successfully had implanted neurons, created in laboratory conditions, connect with the brains of mice and both send and receive signals.

In research published Monday in the journal Proceedings of the National Academy of Sciences (PNAS), lead author Jason P. Weick and associates Yan Liu and Su-Chun Zhang describe how they were able to take blank slate human embryonic stem cells (hESC), turn them into neurons, implant them into the brains of laboratory mice and have them successfully fuse with the animals' brains.

"Whether hESC-derived neurons can fully integrate with and functionally regulate an existing neural network remains unknown," Weick and his associates wrote in the abstract of their paper. "Here, we demonstrate that hESC-derived neurons receive unitary postsynaptic currents both in vitro and in vivo and adopt the rhythmic firing behavior of mouse cortical networks via synaptic integration."

"Optical stimulation of hESC-derived neurons expressing Channelrhodopsin-2 elicited both inhibitory and excitatory postsynaptic currents and triggered network bursting in mouse neurons. Furthermore, light stimulation of hESC-derived neurons transplanted to the hippocampus of adult mice triggered postsynaptic currents in host pyramidal neurons in acute slice preparations," they added. "Thus, hESC-derived neurons can participate in and modulate neural network activity through functional synaptic integration, suggesting they are capable of contributing to neural network information processing both in vitro and in vivo."

In short, they were able to take embryonic stem cells, use them to create neurons (which are specialized cells that send and receive signals within the body's central nervous system), implant them into the brains of a different type of living creature, and have them assimilate into a subject's brain well enough to work, at a functional level, as part of a complex system that oversees locomotion, conversation, and even thinking.

Specifically, Weick's team implanted the lab-created neurons into the hippocampus of adult mice. They were able to observe the successful integration of those cells by analyzing live tissue taken from the recipients.

"The big question was can these cells integrate in a functional way," Weick, a scientist at the University of Wisconsin-Madison's Waisman Center, said in a statement. "We show for the first time that these transplanted cells can both listen and talk to surrounding neurons of the adult brain."

They discovered, according to a university press release, that "the human neurons adopted the rhythmic firing behavior of many brain cells talking to one another in unison. And, perhaps more importantly, that the human cells could modify the way the neural network behaved."

The press release also stated that the study "represents a crucial step toward deploying customized cells to repair damaged or diseased brains, the most complex human organ."